According to symmetric encryption, computing devices that are parties to a transaction utilize a common encryption key, sometimes referred to as a session key. A first party encrypts a message with the session key, creating an encrypted first message. The first party sends the encrypted first message to a second party. The second party decrypts the encrypted first message with the session key. To prevent unauthorized parties from decrypting and reading the messages, the session key is kept secret. In order to implement symmetric encryption, however, both the first party and the second party must securely obtain copies of the session key.